Phylogenetic and population genetic analysis of Arunachali Yak (Bos grunniens) using mitochondrial DNA D-loop region.

Abstract

The Arunachali yak (Bos grunniens) is an important breed native to the northeastern Himalayas of India. Understanding its genetic diversity and evolutionary relationships with other bovine species is crucial for effective conservation and breeding strategies. This study investigates the mitochondrial DNA (mtDNA) D-loop region of Arunachali yak and compares it with other bovines to elucidate these relationships. We collected blood samples from 18 Arunachali yak individuals and isolated genomic DNA. The partial mtDNA D-loop region was amplified using PCR and sequenced. Sequences were compared with those from Bos frontalis, Bos gaurus, Bos indicus, Bubalus bubalis, and Capra hircus available in GenBank. Phylogenetic relationships were assessed through Neighbor-Joining trees and median-joining networks. Genetic diversity indices and neutrality tests were applied to evaluate population genetic characteristics. Phylogenetic analysis identified three distinct clades, with Arunachali yak clustering closely with Bos indicus, and forming a separate branch from other bovine species. Median-joining networks revealed six haplogroups, with Arunachali yak uniquely representing Hap_3. Genetic diversity analysis showed no polymorphism within Arunachali yak, indicating very low genetic variation in the selected animal samples. AMOVA demonstrated significant genetic differentiation among populations (Fst = 0.30053, P < 0.001), with a substantial portion of variation occurring within populations. The Arunachali yak exhibits a close genetic relationship with Bos indicus, reflecting recent divergence. The study underscores the distinct genetic profile of Arunachali yak and highlights its limited genetic variability. These findings enhance our understanding of bovine evolutionary relationships and emphasize the need for targeted conservation measures to preserve the genetic integrity of Arunachali yak.